Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China.
State Key Laboratory of Neuroscience, Institute of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.
Cell Death Dis. 2023 Mar 15;14(3):198. doi: 10.1038/s41419-023-05721-3.
The highly widespread and infiltrative nature of glioblastoma multiforme (GBM) makes complete surgical resection hard, causing high recurrence rate and poor patients' prognosis. However, the mechanism underlying GBM migration and invasion is still unclear. In this study, we investigated the role of a Ras-related protein Rab32 on GBM and uncovered its underlying molecular and subcellular mechanisms that contributed to GBM aggressiveness. The correlation of Rab32 expression with patient prognosis and tumor grade was investigated by public dataset analysis and clinical specimen validation. The effect of Rab32 on migration and invasion of GBM had been evaluated using wound healing assay, cell invasion assay, as well as protein analysis upon Rab32 manipulations. Mitochondrial dynamics of cells upon Rab32 alterations were detected by immunofluorescence staining and western blotting. Both the subcutaneous and intracranial xenograft tumor model were utilized to evaluate the effect of Rab32 on GBM in vivo. The expression level of Rab32 is significantly elevated in the GBM, especially in the most malignant mesenchymal subtype, and is positively correlated with tumor pathological grade and poor prognosis. Knockdown of Rab32 attenuated the capability of GBM's migration and invasion. It also suppressed the expression levels of invasion-related proteins (MMP2 and MMP9) as well as mesenchymal transition markers (N-cadherin, vimentin). Interestingly, Rab32 transported Drp1 to mitochondrial from the cytoplasm and modulated mitochondrial fission in an ERK signaling-dependent manner. Furthermore, silencing of Rab32 in vivo suppressed tumor malignancy via ERK/Drp1 axis. Rab32 regulates ERK/Drp1-dependent mitochondrial fission and causes mesenchymal transition, promoting migration and invasion of GBM. It serves as a novel therapeutic target for GBM, especially for the most malignant mesenchymal subtype. Schematic of Rab32 promotes GBM aggressiveness via regulation of ERK/Drp1-mediated mitochondrial fission. Rab32 transports Drp1 from the cytoplasm to the mitochondria and recruits ERK to activate the ser616 site of Drp1, which in turn mediates mitochondrial fission and promotes mesenchymal transition, migration and invasion of GBM.
胶质母细胞瘤（GBM）具有高度广泛和浸润性，使得完全手术切除变得困难，导致高复发率和患者预后不良。然而，GBM 迁移和侵袭的机制仍不清楚。在这项研究中，我们研究了 Ras 相关蛋白 Rab32 在 GBM 中的作用，并揭示了其促进 GBM 侵袭性的潜在分子和亚细胞机制。通过公共数据集分析和临床标本验证，研究了 Rab32 表达与患者预后和肿瘤分级的相关性。通过划痕愈合试验、细胞侵袭试验以及 Rab32 操作后的蛋白分析，评估了 Rab32 对 GBM 迁移和侵袭的影响。通过免疫荧光染色和 Western blot 检测 Rab32 改变后细胞的线粒体动力学。利用皮下和颅内异种移植肿瘤模型评估 Rab32 在体内对 GBM 的影响。Rab32 的表达水平在 GBM 中显著升高，特别是在最恶性的间充质亚型中，并且与肿瘤病理分级和不良预后呈正相关。Rab32 的敲低减弱了 GBM 的迁移和侵袭能力。它还抑制了侵袭相关蛋白（MMP2 和 MMP9）和间充质转化标志物（N-钙黏蛋白、波形蛋白）的表达水平。有趣的是，Rab32 将 Drp1 从细胞质转运到线粒体，并以 ERK 信号依赖性方式调节线粒体裂变。此外，体内沉默 Rab32 通过 ERK/Drp1 轴抑制肿瘤恶性程度。Rab32 调节 ERK/Drp1 依赖性线粒体裂变并引起间充质转化，促进 GBM 的迁移和侵袭。它是 GBM 的一种新的治疗靶点，特别是对最恶性的间充质亚型。示意图显示 Rab32 通过调节 ERK/Drp1 介导的线粒体裂变促进 GBM 的侵袭性。Rab32 将 Drp1 从细胞质转运到线粒体，并募集 ERK 激活 Drp1 的 ser616 位点，从而介导线粒体裂变并促进 GBM 的间充质转化、迁移和侵袭。
